Electromagnetic structure optimization method of electromagnetic eddy current brake and cooling system construction method thereof

Abstract

The present invention discloses an electromagnetic structure optimization method of an electromagnetic eddy current brake and a cooling system construction method thereof, and relates to the technical field of electromagnetic eddy current brakes. The present invention uses a finite element three-dimensional modeling module to model a DS-50 type electromagnetic eddy current brake, and performs simulation analysis on it to determine the influence of structural parameters, objectively determine the optimal structural parameters of the electromagnetic eddy current brake, ensure the performance effect of the electromagnetic eddy current brake, and improve the operating stability of the electromagnetic eddy current brake; use the BBD method to construct an orthogonal test table corresponding to the structural parameters, and conduct simulation research to determine the optimal structural parameters when the braking torque is maximum and the rotor eddy current loss is minimum; use the polynomial regression method to construct a response surface model to determine the temperature distribution of the electromagnetic eddy current brake, and combine the water-cooled heat dissipation structure to construct a cooling system to reduce the temperature of the electromagnetic eddy current brake during long-term working, dissipate heat, and ensure the working performance, safety and service life of the electromagnetic eddy current brake.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic eddy current brakes, and in particular to an electromagnetic structure optimization method of an electromagnetic eddy current brake and a cooling system construction method thereof. Background Art

[0002] As an auxiliary braking device for drilling machinery, electromagnetic eddy current brake has the advantages of low noise, low pollution, low wear, high reliability, etc., which greatly improves the efficiency and equipment level of drilling operations. It adopts the principle of electromagnetic induction, generates braking torque through eddy currents in the rotor, and realizes the control of the rotation speed of the winch drum. However, there are still some problems to be solved in the research of electromagnetic eddy current brake. There is a lack of accurate and effective optimization method for the electromagnetic structure of electromagnetic eddy current brake, and there is subjectivity in the setting of size parameters, so that the braking torque of electromagnetic eddy current brake cannot be determined and the stability of operation is reduced; and it is difficult to determine the optimal structural parameters of electromagnetic eddy current brake, and the corresponding performance effect cannot be guaranteed, so the working efficiency of electromagnetic eddy current brake will be reduced. In addition, since electromagnetic eddy current brake generates a lot of heat during long-term operation, the brake temperature rises, which in turn affects the performance and service life of the brake. Therefore, a cooling system construction method is needed to reduce the temperature of electromagnetic eddy current brake during long-term operation, dissipate heat, and ensure the working performance, safety and service life of electromagnetic eddy current brake. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the electromagnetic structure optimization method of the electromagnetic eddy current brake and the cooling system construction method thereof provided by the present invention solve the problem that the existing methods are subjective in setting the dimensional parameters, which makes it impossible to determine the braking torque of the electromagnetic eddy current brake and reduces the stability of operation; and it is difficult to determine the optimal structural parameters of the electromagnetic eddy current brake, and the corresponding performance effect cannot be guaranteed, so that the working efficiency of the electromagnetic eddy current brake will be reduced.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] A method for optimizing the electromagnetic structure of an electromagnetic eddy current brake is provided, which comprises the following steps:

[0006] S1. Obtaining the size parameters of the electromagnetic structure of the electromagnetic eddy current brake;

[0007] S2, modeling the electromagnetic structure based on various size parameters and using a finite element three-dimensional modeling module to obtain a corresponding three-dimensional parameter stereo model;

[0008] S3, based on the three-dimensional parameter stereo model in step S2, using the electromagnetic module to simulate and analyze the braking characteristics of the electromagnetic structure to obtain corresponding analysis results;

[0009] S4. Based on the analysis results, the response surface method is used to optimize the electromagnetic structure to obtain the optimized electromagnetic structure, thereby completing the optimization of the electromagnetic structure.

[0010] A method for constructing a cooling system is provided, comprising the following steps:

[0011] P1. Based on the optimized electromagnetic structure, build the corresponding three-dimensional thermal analysis model;

[0012] P2. Analyze the temperature distribution of the three-dimensional thermal analysis model using the transient temperature field finite element method to obtain the corresponding temperature distribution analysis results;

[0013] P3, obtain the actual temperature distribution of the optimized electromagnetic structure;

[0014] P4. Based on the temperature distribution analysis results and the actual temperature distribution, a water cooling structure is selected and the cooling system is constructed using SolidWorks modeling software.

[0015] The beneficial effects of the present invention are:

[0016] 1. Optimization method: The stator, rotor and excitation coil of the DS-50 electromagnetic eddy current brake are modeled using the finite element three-dimensional modeling module, and simulation analysis is performed to determine the tooth head width W. 1 , the length of the fourth middle tooth is L 4 、Inner tooth length L 5 As well as the influence of the working air gap length δ on the braking torque, the optimal structural parameters of the electromagnetic eddy current brake are objectively determined to ensure the performance of the electromagnetic eddy current brake and further improve the operating stability of the electromagnetic eddy current brake;

[0017] 2. Cooling system construction method Based on the optimized electromagnetic structure, the tooth head width W is constructed using the BBD method. 1 , length of the fourth middle tooth L 4 、Inner tooth length L 5 As well as the orthogonal test table corresponding to the working air gap length δ, and conduct simulation research to determine the optimal structural parameters when the braking torque is maximum and the rotor eddy current loss is minimum; use the polynomial regression method to construct a response surface model, solve the response surface model, determine the temperature distribution of the electromagnetic eddy current brake, and build a cooling system in combination with the water-cooled heat dissipation structure to reduce the temperature of the electromagnetic eddy current brake during long-term working process, dissipate heat, and ensure the working performance, safety and service life of the electromagnetic eddy current brake. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flow chart of the electromagnetic structure optimization method;

[0019] Figure 2 It is a schematic diagram of stator structure size parameters;

[0020] Figure 3 It is a three-dimensional parametric stereo model;

[0021] Figure 4 It is a finite element simulation model;

[0022] Figure 5 is the braking torque and the tooth head width W 1 The relationship curve diagram of

[0023] Figure 6 is the braking torque and tooth root width W 2 The relationship curve diagram of

[0024] Figure 7 is the braking torque and the length of the fourth middle tooth L 4 The relationship curve of

[0025] Figure 8 is the braking torque and the inner tooth length L 5 The relationship curve diagram of

[0026] Fig. 9 is the relationship curve between braking torque and rotor thickness h;

[0027] Fig.10 is the relationship curve between braking torque and working air gap length δ;

[0028] Fig.11 Construct a method flow chart for the cooling system;

[0029] Fig.12 It is a simulation model for temperature field;

[0030] Fig.13 It is a schematic diagram of the cooling system;

[0031] Fig.14 This is the temperature distribution cloud diagram of electromagnetic eddy current brake after water cooling;

[0032] Fig.15 is the stator temperature distribution cloud diagram;

[0033] Fig.16 is the winding temperature distribution cloud diagram;

[0034] Fig.17 This is the rotor temperature distribution cloud diagram. DETAILED DESCRIPTION

[0035] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0036] like Figure 1 As shown, a method for optimizing the electromagnetic structure of an electromagnetic eddy current brake comprises the following steps:

[0037] S1. Obtaining the size parameters of the electromagnetic structure of the electromagnetic eddy current brake;

[0038] The electromagnetic structure adopts DS-50 electromagnetic eddy current brake, and the corresponding performance parameters are shown in Table 1:

[0039] Table 1 DS-50 electromagnetic eddy current brake performance parameters

[0040] name Numeric Braking torque 60kN.m Drilling depth 5000m Number of excitation coils 4 Rated resistance of each excitation coil 6.5Ω Rated speed 50rpm Excitation current 40ADC

[0041] The DS-50 electromagnetic eddy current brake includes two sets of stators, four excitation coils and a rotor on the same central axis; among which:

[0042] There is a working air gap between the stator and the rotor; the working air gap, the stator, the rotor and the excitation coil constitute a magnetic circuit;

[0043] Each set of stators includes an inner yoke, a middle yoke and an outer yoke; both sets of stators are inside the rotor, respectively located on both sides of the rotor; the inner yoke and the outer yoke are symmetrically placed on both sides of the middle yoke and have the same shape; the four excitation coils are connected in a two-in-two-in-parallel manner and are located in the working air gap between the stator and the rotor;

[0044] The inner magnetic yoke includes an isosceles trapezoidal body component, a right-angled trapezoidal body component and a semi-fusiform body component; the right-angled trapezoidal body component and the isosceles trapezoidal body component are an integrated component, and the right-angled trapezoidal body component is placed on the upper side of the isosceles trapezoidal body component, and the semi-fusiform body component is located on the upper side of the right-angled trapezoidal body component;

[0045] The middle magnetic yoke is a shuttle-shaped component, with a groove on each side, forming an "I" shape;

[0046] The size parameters of the electromagnetic structure include the size parameters of the rotor, the size parameters of the stator, the size parameters of the coil and the working air gap length δ;

[0047] The size parameters of the rotor include the rotor outer radius rotor-out, the rotor inner radius rotor-inner and the rotor width rotor-width;

[0048] like Figure 2 As shown, the stator size parameters include the length of the first outer yoke R 1 , the length of the second middle yoke is R 2 , the length of the third intermediate yoke is R 3 , the length of the fourth intermediate yoke is R 4 , the outer fifth yoke length R 5 , the length of the sixth outer yoke is R 6 , the length of the outer seventh yoke is R 7 , length of the first middle tooth L 1 , the length of the second middle tooth L 2 , length of the third middle tooth L 3 , length of the fourth middle tooth L 4 、Inner tooth length L 5 , Tooth head width W 1 , tooth root width W 2 、Intermediate tooth length W 3 ;

[0049] The size parameters of the coil include the coil outer radius coil-out, the coil inner radius coil-inner and the coil width coil-width.

[0050] S2. Based on the size parameters, the electromagnetic structure is modeled using the finite element three-dimensional modeling module to obtain the corresponding three-dimensional parameter stereo model, such as Figure 3 As shown;

[0051] The rotor of the electromagnetic eddy current brake is connected to the winch drum shaft through a gear clutch, driven by the winch drum, and rotates at the same speed as the drum. The rotor is part of the magnetic circuit, and together with the stator and the working air gap, it forms a complete magnetic circuit for the brake. The rotor structural dimension parameters, stator structural dimension parameters, and excitation coil dimension parameters are shown in Table 2, Table 3, and Table 4, respectively.

[0052] Table 2 Rotor structural dimension parameters

[0053] name symbol Value / mm Rotor outer radius rotor-out 718 Rotor inner radius rotor-inner 698 Rotor width rotor-width 726

[0054] Table 3 Stator structure dimension parameters

[0055]

[0056]

[0057] Table 4 Rotor structural dimension parameters

[0058] name symbol Value / mm Excitation coil outer radius coil-out 646 Inner radius of excitation coil Coil-inner 575 Excitation coil width coil-in 45

[0059] S3, based on the three-dimensional parameter stereo model in step S2, using the electromagnetic module to simulate and analyze the braking characteristics of the electromagnetic structure to obtain corresponding analysis results;

[0060] When simulating and analyzing the braking characteristics of electromagnetic structures, in order to simplify the electromagnetic eddy current braking analysis model and improve the calculation efficiency, the following assumptions need to be made for the analysis model:

[0061] (1) When establishing the model, only the electromagnetic-related parts are considered, and the electromagnetic eddy current brake is simplified into three parts: stator, rotor and coil; (2) The influence of temperature on conductivity and magnetic permeability is ignored; (3) The deformation of each component during actual movement is not considered, and the elastic deformation of each component is ignored; 4) In order to reduce the amount of finite element simulation calculations, some water channel connections, chamfers and fillets in the model are simplified.

[0062] The electromagnetic module in step S3 adopts the electromagnetic module of finite element software.

[0063] The braking characteristics in step S3 include magnetic field characteristics and torque characteristics.

[0064] Step S3 includes the following steps:

[0065] S3-1, preset the grid size and based on the three-dimensional parameter stereo model in step S2, use finite element simulation software to create a band domain, and surround the three-dimensional parameter stereo model in step S2; create a solution region region, and surround the band domain, such as Figure 4 As shown, the corresponding finite element simulation model is obtained; in addition, the band domain is an entity that wraps all motion areas. During the entire simulation time, the band domain must be simulated once for each step length of movement;

[0066] The mesh size of the software adaptive division is generally large, so the mesh division is performed by presetting the maximum mesh size of important components. If the mesh division is too fine, it will significantly increase the calculation time. For the excitation coil, since it has little effect on the torque of the electromagnetic eddy current brake model, a relatively coarse mesh division can be used, so the mesh size of the coil is set to 110mm; the stator and rotor are the main paths for the magnetic field to pass through, and the division of the internal mesh of the stator and rotor is set to 90mm in this model; the size of the maximum mesh side length inside the band domain is set to 100mm.

[0067] Since electromagnetic eddy current brakes require fast response and stable braking torque, the selected materials need to have low residual magnetism, high magnetic permeability and good stability. Therefore, in the finite element simulation model, the stator and rotor materials are set to low carbon steel steel-1010; the excitation coil material is set to copper, and the rest of the material is set to vacuum.

[0068] S3-2, setting the excitation, the number of turns of the excitation coil, the excitation current value, the boundary conditions and the simulation parameters, simulating the magnetic field characteristics and the torque characteristics of the electromagnetic structure through the finite element simulation model, and obtaining the corresponding braking torque data;

[0069] When setting the excitation, the number of coil turns and the current value can be defined by assigning winding properties to the coil cross section. According to the working principle of electromagnetic eddy current brakes, two adjacent coils form a magnetic pole. When energized, the coil currents are in opposite directions. When this magnetic pole is working, it generates magnetic fields with different positive and negative poles. When setting the simulation of the coil model, find the intersection of the solid coil and the XZ axis, perform Boolean separation on the intersection and the coil, and then select this surface to add excitation, setting the number of turns to 413 turns. Then add the winding to the model, set the excitation current to 20A, and set the magnitude and direction of the excitation current for the coil through this current source excitation section. The rotor will generate induced eddy currents during operation, so the eddy current effect must be checked in the excitation source settings. At the same time, the finite element calculation is a huge matrix equation, and boundary conditions need to be set in order to find a unique solution.

[0070] The number of turns of the excitation coil in step S3-2 is 413, the excitation current value is 20A, the boundary condition is that the tangential component of the magnetic field intensity is always zero, and the simulation parameters include the rotation speed, simulation time and simulation step size, which are 50rpm, 100ms and 5ms respectively.

[0071] Among them, the average braking force data is 57.47 kN.m, and the corresponding simulation results converge, which is 4.2% different from the actual requirement of 60 kN.m for electromagnetic eddy current brakes under rated conditions, which is less than 5% in statistical significance and is within the error range, verifying the feasibility of the simulation model.

[0072] S3-3, obtaining influencing factors related to the braking torque of the electromagnetic structure;

[0073] The influencing factors related to the braking torque of the electromagnetic structure in step S3-3 include the tooth head width W 1 , tooth root width W 2 , length of the fourth middle tooth L 4 、Inner tooth length L 5 , rotor thickness h and working air gap length δ.

[0074] S3-4. Analyze the braking torque data and influencing factors, that is, select an influencing factor and change the numerical value of the influencing factor, and perform simulation while keeping the numerical values ​​of other influencing factors unchanged to obtain the corresponding relationship curve graph, that is, obtain the corresponding analysis result.

[0075] like Figure 5 As shown, the tooth head width W 1In the range of 0mm to 15mm, the braking torque of the electromagnetic eddy current brake shows a trend of gradual increase, but the increase gradually slows down. When it exceeds 15mm, the braking torque of the electromagnetic eddy current brake shows a downward trend. 1 When it is 15mm, the braking torque reaches its maximum value, which is 58kN.m.

[0076] like Figure 6 As shown in the figure, under the premise of keeping other structural parameters of electromagnetic eddy current brake unchanged, the tooth root width W 2 Set it as a linear variable and calculate the tooth root width W of the electromagnetic eddy current brake under rated conditions. 2 A parametric simulation analysis was carried out. As the tooth root width W 2 As the diameter increases from 40mm to 70mm, the braking torque of the electromagnetic eddy current brake gradually increases, but the increase gradually slows down. When it exceeds 70mm, it finally shows a downward trend. 2 When it is 70mm, the braking torque of the electromagnetic eddy current brake reaches its maximum value, which is 57.67kN.m.

[0077] like Figure 7 As shown in the figure, under the premise of keeping other structural parameters of the electromagnetic eddy current brake unchanged, the length of the fourth middle tooth is set as a linear variable, and a parametric simulation analysis is carried out for the electromagnetic eddy current brake under rated working conditions. 4 In the process of increasing from 240mm to 270mm, the braking torque of the electromagnetic eddy current brake shows a trend of gradual increase, and the increase gradually slows down. When it exceeds 270mm, the braking torque finally shows a downward trend. 4 When it is 270mm, the electromagnetic eddy current brake torque reaches its maximum value, which is 57.47kN.m.

[0078] like Figure 8 As shown in the figure, under the premise of keeping other structural parameters of electromagnetic eddy current brake unchanged, the inner tooth length L 5 It is set as a linear variable, and a parametric simulation analysis of the electromagnetic eddy current brake is carried out under rated working conditions. 5 When gradually increasing from 110mm to 160mm, the braking torque of the electromagnetic eddy current brake also increases accordingly, but the increase gradually slows down.

[0079] like Fig. 9As shown in the figure, the electromagnetic eddy current brake rotor is an important part of the braking system. As a carrier of eddy current, its thickness will directly affect the magnitude of the magnetic field strength. If the rotor thickness is too thin, it is easy to cause magnetic saturation. On the contrary, if the rotor thickness is too thick, it will not only increase the magnetic resistance and reduce the heat dissipation effect, but also increase the overall weight, which will have an adverse effect on the magnitude of the braking torque. Under the premise of keeping other structural parameters of the electromagnetic eddy current brake unchanged, the rotor thickness h is set as a linear variable. Under rated operating conditions, the finite element simulation software is used to perform parametric simulation analysis. When the rotor thickness h increases from 5mm to 30mm, the braking torque rises rapidly with the increase of the rotor thickness h. When the rotor thickness h is 30mm to 50mm, the braking torque becomes stable and does not change with the increase of the rotor thickness h, floating around 57.47kN.m. Taking various factors into consideration, the rotor thickness h is selected as 20mm.

[0080] like Fig.10 As shown in the figure, the working air gap, as a non-magnetic component in the electromagnetic eddy current brake magnetic circuit, has a significant impact on the loss and electromagnetic characteristics of the electromagnetic eddy current brake. In order to further explore the influence of the working air gap length δ on the braking torque of the electromagnetic eddy current brake, the other structural parameters of the electromagnetic eddy current brake are kept unchanged, and the working air gap length δ is set as a linear variable. Under rated working conditions, the braking torque of the electromagnetic eddy current brake under different working air gap lengths δ is calculated using finite element simulation software. With the increase of the working air gap length δ, the braking torque gradually decreases. This is because the increase in the working air gap length δ will lead to an increase in the air gap magnetic resistance, thereby weakening the air gap magnetic field and reducing the braking torque. However, if the air gap is too small, magnetic saturation may occur. Therefore, it is necessary to select an air gap value that can both reduce the magnetic saturation phenomenon and meet the braking torque requirements. Usually, the working air gap length δ ranges from 0.73 to 1.27 mm.

[0081] S4. Based on the analysis results, the response surface method is used to optimize the electromagnetic structure to obtain the optimized electromagnetic structure, thereby completing the optimization of the electromagnetic structure.

[0082] Step S4 includes the following steps:

[0083] S4-1. Based on the analysis results of step S3-4, different structural parameters have different effects on the electromagnetic eddy current brake torque, which can also be called different sensitivity of variables, so the tooth head width W is selected. 1 , tooth root width W 2 , length of the fourth middle tooth L 4 、Inner tooth length L 5 and the working air gap length δ as the initial optimized size parameter;

[0084] S4-2, taking the braking torque and rotor eddy current loss as optimization targets respectively, and using Taguchi optimization design method to determine the initial optimization size parameters;

[0085] Taguchi optimization design method is a design method that focuses on local optimization. Compared with the global optimization design method, it has the following significant advantages. First, the establishment of its objective function is relatively simple, the calculation cycle is short, the convergence speed is fast, the efficiency is high, and the optimal combination parameters of multi-objective optimization can be quickly and effectively searched. Multi-objective optimization design can be realized, so that the problems encountered in practice can be solved more comprehensively. In the optimization process, many methods currently used are single-parameter optimization studies, and their influence on the performance of electromagnetic eddy current brakes is determined only based on a single change. However, there are high coupling and multiple constraints between the parameters of electromagnetic eddy current brakes. Therefore, it is more appropriate to convert the optimization problem into a multi-parameter multi-objective optimization strategy for processing. Multi-objective optimization can comprehensively consider the various structural parameters of electromagnetic eddy current brakes, so that while improving one of the performance indicators, other performance indicators will not be sacrificed. This method can explore the design space more comprehensively and find an optimal solution that balances various performances from many possible solutions. Therefore, the Taguchi optimization design method is selected to determine the initial optimization size.

[0086] Taguchi optimization design method includes the following specific steps:

[0087] S4-2-1, using the initial optimized size parameters as optimization factors;

[0088] S4-2-2, determine the best value range of the optimization factor;

[0089] S4-2-3. Determine the optimization factor level value;

[0090] The optimization factors are repeatedly adjusted and simulated using the finite element simulation module to determine the corresponding optimal value range; tooth head width W 1 , tooth root width W 2 , length of the fourth middle tooth L 4 、Inner tooth length L 5 The optimal range of the working air gap length δ is shown in Table 5. Four influence levels are selected equidistantly within these optimal ranges. These four level values ​​are named level 1, 2, 3, and 4 in order from small to large, and the detailed level value data are shown in Table 6.

[0091] Table 5 Optimal value range of optimization factors

[0092] Optimization Factor Value range / mm <![CDATA[W 1 ]]> 12-20 <![CDATA[W 2 ]]> 65-80 <![CDATA[L 4 ]]> 265-275 <![CDATA[L 5 ]]> 145-165 δ 0.75-1.25

[0093] Table 6 Optimized factor level numbers

[0094] Optimization Factor Level 1 Level 2 Level 3 Level 4 <![CDATA[W 1 ]]> 14 16 18 20 <![CDATA[W 2 ]]> 65 70 75 80 <![CDATA[L 4 ]]> 266 268 270 272 <![CDATA[L 5 ]]> 145 150 155 160 δ 0.8 0.9 1 1.1

[0095] S4-2-4, construct an orthogonal test table;

[0096] According to the five optimization factors selected in Tables 5 and 6 and the corresponding four level values, the L 16 (4 5 ) Orthogonal table. If a single-objective, single-variable comprehensive experiment is conducted, a total of 1024 experiments are required. Using the Taguchi optimization design method for orthogonal experiments, only 16 experiments are needed to achieve multi-objective, multi-variable optimization design, which greatly reduces the amount of calculation.

[0097] The finite element method was used to construct 16 electromagnetic eddy current brake models and simulate them. The corresponding simulation results are shown in Table 7:

[0098] Table 7 Orthogonal table of optimization factor levels and finite element simulation results

[0099] Serial number <![CDATA[W 1 / mm]]> <![CDATA[W 2 / mm]]> <![CDATA[L 4 / mm]]> <![CDATA[L 5 / mm]]> δ / mm T / kN.m <![CDATA[P eddy / kW]]> 1 14 65 266 145 0.8 57.13 301.4 2 14 70 268 150 0.9 58.41 298.74 3 14 75 270 155 1.0 57.34 294.55 4 14 80 272 160 1.1 55.82 288.2 5 16 65 268 155 1.1 55.65 288.84 6 16 70 266 160 1.0 57.68 295.01 7 16 75 272 145 0.9 59.81 308.16 8 16 80 270 150 0.8 53.21 307.11 9 18 65 270 160 0.9 60.71 317.94 10 18 70 272 155 0.8 62.73 320.66 11 18 75 266 150 1.1 55.13 281.87 12 18 80 268 145 1.0 57.68 297.85 13 20 65 272 150 1.0 58.67 299.14 14 20 70 270 145 1.1 49.4 274.84 15 20 75 268 160 0.8 63.44 330.27 16 20 80 266 155 0.9 59.4 313

[0100] Where, T represents the braking torque value, P eddy Indicates rotor eddy current loss.

[0101] S4-2-5. Analyze the mean and variance of the orthogonal test table;

[0102] In order to study the influence of parameter changes of electromagnetic eddy current brake optimization factors on the optimization objectives, the experimental data statistical analysis was carried out based on the previously established orthogonal test table and finite element analysis results. In order to obtain the influence of each optimization factor on each optimization objective, the average value and variance analysis are required. The average values ​​of the performance indicators of the optimization factors at different levels are shown in Table 8:

[0103] Table 8 Orthogonal table of optimization factor levels and finite element simulation results

[0104]

[0105] From Table 8, we can see that the optimal factor combination that can maximize the braking torque T is: tooth head width W 1 (3) Tooth root width W 2 (3) The length of the fourth tooth in the middle is L 4 (4) Inner tooth length L 5 (4) and the working air gap length δ(2);

[0106] In order to select the best combination of electromagnetic eddy current brake optimization parameters, it is necessary to understand the influence weights of these five optimization parameters on various performance indicators, using the formula:

[0107]

[0108] The variance analysis was performed on the simulation results to more accurately understand the influence of each parameter on the performance index. Where Xi represents the optimization factor X at the i-th level, N represents the total number of parameters, S represents, ∑(·) represents the summation function, SS represents the variance, and m Xi (S) represents the average value of a certain optimization target under the optimization factor X level, and m(S) represents the average value of the optimization target. The influence of electromagnetic eddy current brake optimization factor on different performance indicators is shown in Table 9:

[0109] Table 9 Effects of various optimization factors on different performance indicators of electromagnetic eddy current brakes

[0110]

[0111] It can be seen from Table 9 that the higher the ratio of the design variables, the greater the impact on the optimization objective.

[0112] S4-2-6. Determine the optimization parameter c based on the analysis result of step S4-2-5, and use the best level combination as the initial optimization result, that is, the initial optimization size parameter.

[0113] Combining the contents of Table 8 and Table 9, the electromagnetic eddy current brake and rotor eddy current losses are affected by the tooth root width W. 2 The total weight of the influence is small, so the tooth head width W is selected 1 , length of the fourth middle tooth L 4 、Inner tooth length L 5 The four structural parameters of working air gap length δ are further optimized as the final optimization variables. The working air gap length δ has the largest influence on the rotor eddy current loss, reaching 73.47%, so the rotor eddy current loss should be selected at the level with the smallest rotor eddy current loss. The influence of the other optimization factors on the braking torque is greater than the rotor eddy current loss, so the level with the largest braking torque should be selected. The optimal level combination is shown in Table 10:

[0114] Table 10

[0115]

[0116]

[0117] S4-3, using the BBD method to establish a response surface model;

[0118] Response surface methodology, also known as response surface design method, is a commonly used method for optimization through experiments. The core of this method is to be able to establish a functional relationship between dependent variables and independent variables within a large interval of the variable space. The basic idea of ​​this method is to select specific sample points in a given variable interval, and then use the response calculation values ​​or experimental values ​​at these sample points to establish a fitting function equation through regression analysis, which is the so-called response surface. This method is particularly suitable for describing complex nonlinear optimization problems, in which the objective function and constraint function may exist in implicit form.

[0119] Commonly used design methods for constructing response surface include central composite design (CCD design) and Box-Behnken design (BBD design). BBD design can reduce the number of experiments, while CCD has more experiments. In addition, when designing CCD, the levels of some factors may exceed the preset limits, while BBD can ensure that the levels of each factor are within the preset range. Considering that the parameter level of electromagnetic eddy current brake is restricted by multiple indicators, this paper selects BBD method to construct response surface model to avoid a series of design errors caused by exceeding the design range.

[0120] The tooth head width W 1 , length of the fourth middle tooth L 4 、Inner tooth length L 5 As well as the working air gap length δ, four structural parameters are used as design variables, and the three levels of each of the four design variables are coded as -1, 0 and +1. The water quality value table of each design variable is constructed, as shown in Table 11:

[0121] Table 11

[0122] Factor number Design variables -1 0 1 A <![CDATA[W 1 ]]> 16 18 20 B <![CDATA[L 4 ]]> 269 272 275 C <![CDATA[L 5 ]]> 159 160 161 D δ 1 1.1 1.2

[0123] According to Table 11, if all permutations and combinations are performed, 81 experiments are required, while the BBD method corresponding to the four design variables only needs 29 experiments, which greatly reduces the calculation time. Through finite element simulation, 29 modelings are performed, and the factor data obtained are used to construct the BBD experimental method parameter factor level table, as shown in Table 12:

[0124] Table 12

[0125] Serial number <![CDATA[W 1 / mm]]> <![CDATA[L 4 / mm]]> <![CDATA[L 5 / mm]]> δ / mm T / Kn.m <![CDATA[P eddy / kW]]> 1 18 272 160 1.1 62.21 310.93 2 18 272 161 1 63.81 327.05 3 18 272 160 1.1 62.21 310.93 4 18 275 160 1.2 58.93 304.88 5 18 269 160 1 64.78 326.75 6 18 269 161 1.1 61.24 314.07 7 20 272 160 1.2 60.17 306.39 8 18 272 159 1 63.82 324.81 9 16 272 161 1.1 61.16 312.53 10 18 272 161 1.2 58.63 304.71 11 18 275 159 1.1 60.76 312.98 12 16 275 160 1.1 60.15 311.01 13 16 272 160 1 64.42 324 24 14 18 275 161 1.1 60.01 320.42 15 18 272 159 1.2 60.48 303.11 16 20 272 160 1 65.53 332.06 17 20 275 160 1.1 61.45 319.95 18 20 269 160 1.1 61.85 315.91 19 18 272 160 1.1 62 21 310.93 20 16 272 159 1.1 61.77 312.85 21 20 272 159 1.1 62.85 314.29 22 18 272 160 1.1 62 21 310.93 23 18 269 160 1.2 60.45 301.81 24 18 275 160 1 63.51 330.05 25 18 269 159 1.1 62 15 318.11 26 20 272 161 1.1 61.91 321.95 27 16 269 160 1.1 62.45 312 88 28 16 272 160 1.2 60.52 298 93 29 18 272 160 1.1 62.21 310.93

[0126] Since there is a complex nonlinear relationship between the optimization factor and the optimization target, it is difficult to obtain an accurate expression, so only the response surface model is used to construct an approximate function to approximate the true function. The methods for constructing the response surface model mainly include polynomial regression, artificial neural network, kriging function and radial basis function. In view of the fact that the artificial neural network method and kriging function fitting are time-consuming, the radial basis function is suitable for surface reconstruction, and the polynomial regression method is suitable for dealing with low-order problems with few variables, and has the characteristics of high accuracy and fast convergence speed. Therefore, this paper comprehensively considers and selects the polynomial regression method for response surface modeling.

[0127] The tooth head width W 1 , the length of the fourth middle tooth is L 4 、Inner tooth length L 5 and the working air gap length δ as independent variables, and the braking torque T and the rotor eddy current loss P eddy As the response value, the response surface model is constructed using the polynomial regression method, and the corresponding formula is:

[0128]

[0129] Among them, β 0 , β i , β ii , β ij represents the regression coefficient, x i 、x j They represent the i-th independent variable and the j-th independent variable respectively, ε represents the fitting error, N represents the number of independent variables, and Y represents the response value.

[0130] Since the tooth head width W 1 , the length of the fourth middle tooth is L 4 、Inner tooth length L 5 As well as the optimization range of the working air gap length δ, when constructing the response surface model, it is necessary to encode the independent variables, and the corresponding transformation rule is:

[0131]

[0132] Among them, max represents the maximum value function, min represents the minimum value function, Indicates tooth head width W 1 , the length of the fourth middle tooth is L 4 、Inner tooth length L 5 And the normalized parameter corresponding to the working air gap length δ.

[0133] Based on the parameter factor level table of the BBD experimental method, the braking torque T and the rotor eddy current loss P are obtained using the response surface model formula. eddy The corresponding fitting regression equation is:

[0134] T=62.21+0.2742×A-0.6758×B-0.4225×C-2.22×D+0.4750×A×B-0.0825×A×C-0.3650×A×D+0.04×B×C-0.0625×B×D-0.46×C×D+0.1404×A 2 -0.6721×B 2 -0.5646×C 2 +0.2429×D 2 P eddy =310.93+3.18×A+0.8133×B+1.21×C-12.09×D+1.48×A×B+2×A×C-0.09×A×D+2.87×B×C-0.0575×B×D-0.16×C×D+1.92×A 2 +2.65×B 2 +2.41×C 2 +2.14×D 2

[0135] Where A represents the stator tooth head width W 1 , B represents the length of the fourth middle tooth of the stator L 4 , C represents the inner tooth length L of the stator 5 , D represents the working air gap length δ.

[0136] The present invention adopts the multiple correlation coefficient R y 2 , Correction determination coefficient AdjR 2 , Correction determination coefficient P red R 2 And the model p y As shown in Table 13, the braking torque T and rotor eddy current loss P eddy The corresponding multiple correlation coefficient R y 2 are close to 1, model p y The values ​​are all less than 0.001, and the correction coefficient AdjR 2 , Correction determination coefficient P red R 2 If the differences between them are all within 0.2, it means that the response surface model has good correlation, strong rationality and high accuracy.

[0137] Table 13

[0138] Rating indicators Braking torque T <![CDATA[Rotor eddy current loss P eddy > <![CDATA[R y 2 ]]> 0.9896 0.9904 <![CDATA[AdjR 2 ]]> 0.9792 0.9807 <![CDATA[P red R 2 ]]> 0.9401 0.9445 <![CDATA[p y ]]> <0.0001 <0.0001

[0139] S4-4. Calculate the initial optimized size parameters using the response surface model to obtain the final optimized size parameters. After calculation, when the tooth head width W 1 16mm, the length of the fourth tooth in the middle is L4 270.55mm, inner tooth length L 5 When the working air gap length is 159.94 mm and the working air gap length δ is 1.117 mm, the electromagnetic eddy current brake torque T reaches the maximum value of 62.198 kN.m, and the rotor eddy current loss P eddy The minimum value is 308.796kW. In order to reduce the manufacturing difficulty of electromagnetic eddy current brake, the length of the fourth tooth in the middle is L 4 Adjusted to 270mm, inner tooth length L 5 Adjust to 160mm and the working air gap length δ to 1.1mm.

[0140] S4-5. Apply the final optimized size parameters to the electromagnetic structure to obtain an optimized electromagnetic structure.

[0141] Finite element simulation was performed on the optimized electromagnetic structure and the electromagnetic structure before and after optimization, and the performance was compared. The specific values ​​are shown in Table 14. The braking torque T increased from 57.47 kN.m to 62.21 kN.m, the rotor eddy current loss decreased from 312.67 kW to 308.82 kW, and the torque pulsation K m It is reduced from 1.05% to 0.98%. It can be seen that the electromagnetic structure optimization method of the present invention effectively slows down the temperature rise of the electromagnetic eddy current brake rotor and improves the performance and operation stability of the brake system.

[0142] Table 14

[0143]

[0144]

[0145] like Fig.11 As shown, a cooling system construction method includes the following steps:

[0146] P1. Based on the optimized electromagnetic structure, build the corresponding three-dimensional thermal analysis model;

[0147] In engineering heat transfer phenomena, there are three basic ways of heat transfer: heat conduction, heat convection and heat radiation. In this study of electromagnetic eddy current brake, heat conduction and heat convection are mainly considered, and heat radiation is very small and can be ignored.

[0148] P2. Analyze the temperature distribution of the three-dimensional thermal analysis model using the transient temperature field finite element method to obtain the corresponding temperature distribution analysis results;

[0149] Step P2 includes the following steps:

[0150] P2-1. Set the initial temperature conditions and boundary conditions, determine the thermal conductivity of the material and calculate the losses and flow loads generated by the heat-generating components when the three-dimensional thermal analysis model is running; the initial temperature conditions describe the instantaneous temperature distribution when the electromagnetic eddy current brake starts to conduct heat, and the boundary conditions reflect the heat exchange between the electromagnetic eddy current brake surface and the surrounding medium.

[0151] To analyze the transient temperature field, it is necessary to add boundary conditions to the finite element model. The boundary conditions of the present invention adopt the first type of boundary conditions, assuming that the external surrounding environment is 22°C, and the other boundary conditions are set to ideal adiabatic boundary conditions, that is, the heat flux is set to 0W / m 2 Among them, the first type of boundary condition is to directly specify the exact temperature value on the boundary surface of the object at a specific moment.

[0152] The losses in step P2-1 include stator core loss, copper loss, and rotor eddy current loss; wherein:

[0153] The calculation formula for stator core loss is:

[0154]

[0155] Where α represents the Steinmetz coefficient, B m Indicates the stator flux density amplitude, P h represents the stator hysteresis loss, P e represents the stator eddy current loss, f h 、f e They represent the stator hysteresis magnetic field change frequency and the stator eddy current magnetic field change frequency, respectively. h , K e They represent the stator hysteresis loss coefficient and stator eddy current loss coefficient, respectively. fe Indicates stator core loss;

[0156] The calculation formula for copper loss is:

[0157]

[0158] Among them, I x Represents the effective value of the phase current of the excitation coil, R cu Represents the phase resistance of the excitation coil, P cu Indicates copper loss;

[0159] The calculation formula of rotor eddy current loss is:

[0160]

[0161] Among them, P s Indicates the rotor eddy current loss, L a , L bRespectively represent the axial length and radial length of the rotor, ρ 1 Represents the resistivity of the rotor, V r Indicates the rotor volume, B me Represents the rotor magnetic flux density amplitude, f me represents the magnetic field alternating frequency, k me represents the rotor electromotive force proportional constant;

[0162] The calculation formula for flow load is:

[0163]

[0164] Where H represents the flow load, N m represents turbulent heat transfer, λ m represents the thermal conductivity of air, d represents the characteristic length of fluid flow, and v m 、v l They represent the dynamic viscosity and fluid velocity of the flow, respectively, m , R m They represent Planck number and Reynolds coefficient respectively.

[0165] P2-2, according to the formula:

[0166]

[0167] The heat generation rate q of each heat generating component of the three-dimensional thermal analysis model is obtained; where P s' Represents the loss caused by the heat-generating components, V v Indicates the volume generated by the heat-generating component;

[0168] P2-3. Based on all the data of step P2-1 and step P2-2 and the three-dimensional thermal analysis model, a temperature field simulation calculation model is constructed. Considering the calculation efficiency and the computing power of the computer hardware support software, it is extremely difficult to solve and analyze the temperature field of the complete electromagnetic eddy current brake model. Therefore, according to the circular symmetry of the electromagnetic eddy current brake, the calculation method of the local model is adopted, and one twenty-eighth area of ​​the electromagnetic eddy current brake in the circumferential direction is selected as the calculation model, such as Fig.12 shown.

[0169] In the whole process, because the heat generated by each component is different, it must be accompanied by heat exchange, and the exchange forms include heat conduction, heat convection and heat radiation described above. Under natural cooling conditions, the main focus is on the heat conduction of the contact components of the electromagnetic eddy current brake and the convection heat exchange process with the external air, so the influence of heat radiation is not considered. Considering the complexity of the heat transfer of the internal structure of the electromagnetic eddy current brake, the following assumptions are made for the establishment of the model:

[0170] (1) The external ambient temperature of the electromagnetic eddy current brake is maintained at 22°C;

[0171] (2) The thermal conductivity of the internal air gap is reasonably equivalent to the thermal conductivity of still air, ignoring the changes in heat source caused by uneven temperature distribution.

[0172] (3) The stator and rotor are made of homogeneous materials, and their parameters such as thermal conductivity, density, electrical conductivity and magnetic permeability do not change with changes in temperature.

[0173] P2-4. Solve the temperature field simulation calculation model and obtain the temperature distribution analysis results.

[0174] P3, obtain the actual temperature distribution of the optimized electromagnetic structure;

[0175] Under the condition of continuous operation for 150s and natural cooling, the high temperature area during the operation of the electromagnetic eddy current brake is mainly distributed in the rotor part. The overall temperature of the rotor core temperature distribution is between 226.22℃ and 229.12℃. This is mainly due to the high loss and high heat generated by the rotor. And for the electromagnetic eddy current brake, the eddy current loss generated by the rotor is the main heat source, so the rotor temperature is the highest among all the components of the electromagnetic eddy current brake. The maximum temperature of the stator is 27.701℃, and the maximum temperature of the coil winding is 37.785℃. This is mainly due to the low loss and low heat generated by the stator core and winding, so the temperature of the stator core and winding is lower than the rotor temperature.

[0176] P4. Based on the temperature distribution analysis results and the actual temperature distribution, a water cooling structure is selected and the cooling system is constructed using SolidWorks modeling software.

[0177] In the water-cooled electromagnetic eddy current brake, the cooling water is directly introduced into the empty air gap for cooling. In this way, the rotor surface is immersed in the cooling water, and the entire rotor surface can get sufficient cooling effect during operation. In order to ensure the circulation of cooling water, a water pump is used for forced circulation. At the same time, the three-dimensional modeling of the water channel model of the water-cooling structure was carried out using SolidWorks modeling software. The physical models used for the simulation of the electromagnetic eddy current brake cooling structure are divided into solid area models and fluid area models. In the modeling process, the coolant inlet, coolant outlet, and each wall of the coolant channel are included. The cooling system established is as follows Fig.13 shown.

[0178] In order to compare the temperature field distribution of electromagnetic eddy current brake under natural cooling and water cooling structure, the corresponding material parameters and thermal parameters are set for the electromagnetic eddy current brake model, and the fluid-solid interface is named. Then, the interface type is set for these interfaces, and the overlapping interfaces are combined to create an interface. The interface temperature conduction type is set as coupling, and the finite element analysis is performed. Finally, the overall temperature distribution of the electromagnetic eddy current brake under water cooling conditions when it works continuously for 150s is as follows Fig.14 As shown in the figure, the maximum temperature of the electromagnetic eddy current brake after water cooling is 57.029℃. Compared with the natural cooling, it can be seen that the maximum temperature is reduced by 172.091℃. It can be seen that after the water cooling system is arranged, the maximum temperature of the electromagnetic eddy current brake is significantly reduced, and the cooling effect is obvious. The designed water cooling structure can effectively reduce the temperature of the electromagnetic eddy current brake and ensure its reliable operation. Fig.15 , Fig.16 as well as Fig.17 As shown in the figure, the cooling effect of the rotor is particularly significant because the cooling water structure is close to the rotor of the electromagnetic eddy current brake. The maximum temperature of the rotor is 57.029℃, which is 172.091℃ lower than the maximum temperature under natural cooling conditions. Although the cooling effect of the stator core and winding is not as obvious as that of the rotor, the temperature has also dropped. Specifically, the maximum temperature of the stator has dropped by 5.7℃, and the maximum temperature of the winding has dropped by 13.998℃.

[0179] In summary, the present invention uses the finite element three-dimensional modeling module to model the stator, rotor and excitation coil of the DS-50 electromagnetic eddy current brake respectively, and performs simulation analysis on them to determine the tooth head width W 1 , the length of the fourth middle tooth is L 4 、Inner tooth length L 5 The influence of the working air gap length δ on the braking torque is objectively determined to objectively determine the optimal structural parameters of the electromagnetic eddy current brake, ensure the performance of the electromagnetic eddy current brake, and further improve the operating stability of the electromagnetic eddy current brake; based on the optimized electromagnetic structure, the BBD method is used to construct the tooth head width W 1 , the length of the fourth middle tooth is L 4 、Inner tooth length L 5 As well as the orthogonal test table corresponding to the working air gap length δ, and conduct simulation research to determine the optimal structural parameters when the braking torque is maximum and the rotor eddy current loss is minimum; use the polynomial regression method to construct a response surface model, solve the response surface model, determine the temperature distribution of the electromagnetic eddy current brake, and build a cooling system in combination with the water-cooled heat dissipation structure to reduce the temperature of the electromagnetic eddy current brake during long-term working process, dissipate heat, and ensure the working performance, safety and service life of the electromagnetic eddy current brake.

Claims

1. A method for optimizing the electromagnetic structure of an electromagnetic eddy current brake, characterized in that: The following steps are involved: S1. Obtaining the size parameters of the electromagnetic structure of the electromagnetic eddy current brake; S2, modeling the electromagnetic structure based on various size parameters and using a finite element three-dimensional modeling module to obtain a corresponding three-dimensional parameter stereo model; S3, based on the three-dimensional parameter stereo model in step S2, using the electromagnetic module to simulate and analyze the braking characteristics of the electromagnetic structure to obtain corresponding analysis results; S4. Based on the analysis results, the electromagnetic structure is optimized using the response surface method to obtain an optimized electromagnetic structure, thereby completing the optimization of the electromagnetic structure; The step S4 comprises the following steps: S4-1, based on the analysis results of step S3, the tooth head width , tooth root width , length of the fourth middle tooth , inner tooth length And the working air gap length As the initial optimized size parameter; S4-2, taking the braking torque and rotor eddy current loss as optimization targets respectively, and using Taguchi optimization design method to determine the initial optimization size parameters; S4-3, using the BBD method to establish a response surface model; S4-4, using the response surface model to process the initial optimized size parameters to obtain the final optimized size parameters; S4-5. Apply the final optimized size parameters to the electromagnetic structure to obtain an optimized electromagnetic structure.

2. The electromagnetic structure optimization method of electromagnetic eddy current brake according to claim 1, characterized in that: The electromagnetic structure adopts a DS-50 type electromagnetic eddy current brake and includes two sets of stators, four excitation coils and a rotor on the same central axis; The size parameters of the electromagnetic structure include the size parameters of the rotor, the size parameters of the stator, the size parameters of the coil and the working air gap length. ; The size parameters of the rotor include the rotor outer radius rotor-out, the rotor inner radius rotor-inner and the rotor width rotor-width; The stator dimensions include the length of the first outer yoke , the length of the second middle yoke , length of the third intermediate yoke , length of the fourth intermediate yoke , the outer fifth yoke length , the length of the sixth outer yoke , outer seventh yoke length , length of the first middle tooth , the length of the second middle tooth , length of the third middle tooth , length of the fourth middle tooth , inner tooth length , Tooth head width , tooth root width , Middle tooth length ; The size parameters of the coil include the coil outer radius coil-out, the coil inner radius coil-inner and the coil width coil-width.

3. The electromagnetic structure optimization method of electromagnetic eddy current brake according to claim 2, characterized in that: The braking characteristics in step S3 include magnetic field characteristics and torque characteristics.

4. The electromagnetic structure optimization method of electromagnetic eddy current brake according to claim 3, characterized in that: The step S3 comprises the following steps: S3-1, preset the grid size and based on the three-dimensional parameter stereo model in step S2, use finite element simulation software to create a band domain, and surround the three-dimensional parameter stereo model in step S2; create a solution region region, and surround the band domain to obtain a corresponding finite element simulation model; Among them, the grid size of the excitation coil is 110mm, the grid size of the rotor and stator is 90mm, and the maximum grid side length inside the band domain is 100mm; S3-2, setting the excitation, the number of turns of the excitation coil, the excitation current value, the boundary conditions and the simulation parameters, simulating the magnetic field characteristics and the torque characteristics of the electromagnetic structure through the finite element simulation model, and obtaining the corresponding braking torque data; S3-3, obtaining influencing factors related to the braking torque of the electromagnetic structure; S3-4. Analyze the braking torque data and influencing factors to obtain a corresponding relationship curve diagram, that is, obtain a corresponding analysis result.

5. The electromagnetic structure optimization method of electromagnetic eddy current brake according to claim 4, characterized in that: The number of turns of the excitation coil in step S3-2 is 413, the excitation current value is 20A, the boundary condition is that the tangential component of the magnetic field intensity is always zero, and the simulation parameters include the rotation speed, simulation time and simulation step size, which are 50rpm, 100ms and 5ms respectively.

6. The electromagnetic structure optimization method of electromagnetic eddy current brake according to claim 4, characterized in that: The influencing factors related to the braking torque of the electromagnetic structure in step S3-3 include the tooth head width , tooth root width , length of the fourth middle tooth , inner tooth length , rotor thickness And the working air gap length .

7. A cooling system construction method based on the electromagnetic structure optimization method of the electromagnetic eddy current brake according to any one of claims 1 to 6, characterized in that: The following steps are involved: P1. Based on the optimized electromagnetic structure, build the corresponding three-dimensional thermal analysis model; P2. Analyze the temperature distribution of the three-dimensional thermal analysis model using the transient temperature field finite element method to obtain the corresponding temperature distribution analysis results; P3, obtain the actual temperature distribution of the optimized electromagnetic structure; P4. Based on the temperature distribution analysis results and the actual temperature distribution, a water cooling structure is selected and the cooling system is constructed using SolidWorks modeling software.

8. The cooling system construction method according to claim 7, characterized in that: The step P2 comprises the following steps: P2-1. Set the initial temperature conditions and boundary conditions, determine the thermal conductivity of the material, and calculate the losses and flow loads generated by the heat-generating components when the three-dimensional thermal analysis model is running; P2-2, according to the formula: Get the heat generation rate of each heat generating component of the three-dimensional thermal analysis model ;in, Indicates the loss caused by the heat-generating components. Indicates the volume generated by the heat-generating components; P2-3, based on all the data of step P2-1 and step P2-2 and the three-dimensional thermal analysis model, construct a temperature field simulation calculation model; P2-4. Solve the temperature field simulation calculation model and obtain the temperature distribution analysis results.

9. The cooling system construction method according to claim 8, characterized in that: The losses in step P2-1 include stator core loss, copper loss, and rotor eddy current loss; wherein: The calculation formula for stator core loss is: in, represents the Steinmetz coefficient, represents the stator flux density amplitude, represents the stator hysteresis loss, represents the stator eddy current loss, , They represent the stator hysteresis magnetic field change frequency and the stator eddy current magnetic field change frequency respectively. , They represent the stator hysteresis loss coefficient and stator eddy current loss coefficient respectively. Indicates stator core loss; The calculation formula for copper loss is: in, Indicates the effective value of the phase current of the excitation coil, represents the phase resistance of the excitation coil, Indicates copper loss; The calculation formula of rotor eddy current loss is: in, represents the rotor eddy current loss, , Respectively represent the axial length and radial length of the rotor, represents the resistivity of the rotor, represents the rotor volume, represents the rotor magnetic flux density amplitude, represents the frequency of magnetic field alternation, represents the rotor electromotive force proportional constant; The calculation formula for flow load is: in, represents the flow load, represents turbulent heat transfer, is the thermal conductivity of air, represents the characteristic length of fluid flow, , They represent the dynamic viscosity and fluid velocity of the flow, respectively. , They represent Planck number and Reynolds coefficient respectively.

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